Due to its high cohesive force, an elastomeric fiber such as a polyurethane fiber displays large variations in the frictional forces and tension levels as it is unwound from a cylindrical mandrel (package). Thus, the fraction of the fiber unwound from the outer layer region of the package displays significantly different properties from those unwound from the inner layer region of the package, leading to a non-uniform final product. In other words, there has been the problem that the properties of an elastomeric fiber depend on the winding region of its package.
In order to solve the aforementioned problem, there has been reported a technique to rewind an elastomeric fiber unwound from the package. However, this approach requires an additional rewinding process, resulting in poor productivity and a high manufacturing cost.
U.S. Pat. No. 6,676,054 discloses a method for unwinding a fiber comprising controlling the distance from a fiber package to a fiber guide depending on the tack level of the fiber. Specifically, the distance is equal to at least 41 cm for a fiber with tack of 2 g or more, and 71 to 91 cm for a fiber with tack of 7.5 g or more. However, this method has problems in that the distance must be intermittently and cumbersomely manipulated whenever the tack value varies, which causes poor productivity.
In addition, there has been employed a method for preparing an elastomeric fiber having low tack by way of adding to the starting polymeric resin of an elastomeric fiber an anti-tack agent, e.g., a metal salt of a fatty acid such as magnesium stearate, calcium stearate and sodium stearate, followed by spinning the resulting resin. However, the spun elastomeric fiber obtained by this method suffers from the problem of frequent filament cuts due to a ballooning phenomenon when subjected to be downward unwound.
Accordingly, there has been a need to develop an improved unwinding device which is suitable for unwinding an elastomeric fiber having an anti-tack agent incorporated therein.